U.S. patent application number 13/990676 was filed with the patent office on 2013-11-14 for anti-fog coated article.
This patent application is currently assigned to NIPPON SHEET GLASS CO., LTD.. The applicant listed for this patent is Kazutaka Kamitani, Shuhei Murata, Kazuaki Oya, Toyoyuki Teranishi. Invention is credited to Kazutaka Kamitani, Shuhei Murata, Kazuaki Oya, Toyoyuki Teranishi.
Application Number | 20130302599 13/990676 |
Document ID | / |
Family ID | 46171633 |
Filed Date | 2013-11-14 |
United States Patent
Application |
20130302599 |
Kind Code |
A1 |
Oya; Kazuaki ; et
al. |
November 14, 2013 |
ANTI-FOG COATED ARTICLE
Abstract
The present invention provides an antifog-film-coated article
including an antifog film having high hardness while maintaining
sufficient antifog performance, which article can be employed in
various applications, including antifog mirrors, windowpanes for
automobiles, and windowpanes for buildings. The antifog-film-coated
article of the present invention includes a hard substrate, and a
water-absorbing composite film formed on the substrate, wherein the
water-absorbing composite film contains a polyvinyl acetal resin;
colloidal silica in an amount of 30 to 80 parts by mass on the
basis of 100 parts by mass of the resin; and silica-equivalent
particles derived from a hydrolysis product or partial hydrolysis
product of a silicon alkoxide compound in an amount of 5 to 55
parts by mass on the basis of 100 parts by mass of the resin.
Inventors: |
Oya; Kazuaki;
(Nishinomiya-shi, JP) ; Kamitani; Kazutaka;
(Sakurai-shi, JP) ; Teranishi; Toyoyuki;
(Machida-shi, JP) ; Murata; Shuhei; (Machida-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Oya; Kazuaki
Kamitani; Kazutaka
Teranishi; Toyoyuki
Murata; Shuhei |
Nishinomiya-shi
Sakurai-shi
Machida-shi
Machida-shi |
|
JP
JP
JP
JP |
|
|
Assignee: |
NIPPON SHEET GLASS CO.,
LTD.
Tokyo
JP
|
Family ID: |
46171633 |
Appl. No.: |
13/990676 |
Filed: |
November 14, 2011 |
PCT Filed: |
November 14, 2011 |
PCT NO: |
PCT/JP2011/076217 |
371 Date: |
July 30, 2013 |
Current U.S.
Class: |
428/336 ;
428/426; 428/428 |
Current CPC
Class: |
C09D 129/14 20130101;
C03C 17/006 20130101; C03C 17/009 20130101; G02B 1/10 20130101;
C09D 129/14 20130101; C08G 77/02 20130101; G02B 1/18 20150115; G02B
27/0006 20130101; C08K 3/36 20130101; C09D 5/1668 20130101; C09D
129/14 20130101; Y10T 428/265 20150115; C09K 3/18 20130101; C09D
129/14 20130101; C08K 3/36 20130101; C08K 3/36 20130101; C08K
5/0091 20130101; C03C 1/008 20130101; C09D 5/1618 20130101; C08K
13/02 20130101 |
Class at
Publication: |
428/336 ;
428/426; 428/428 |
International
Class: |
C09K 3/18 20060101
C09K003/18 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 3, 2010 |
JP |
2010-270922 |
Claims
1. An antifog-film-coated article comprising a hard substrate, and
a water-absorbing composite film formed on the substrate,
characterized in that the water-absorbing composite film contains a
polyvinyl acetal resin; colloidal silica in an amount of 30 to 80
parts by mass on the basis of 100 parts by mass of the resin; and
silica-equivalent particles derived from a hydrolysis product or
partial hydrolysis product of a silicon alkoxide compound in an
amount of 5 to 55 parts by mass on the basis of 100 parts by mass
of the resin.
2. An antifog-film-coated article according to claim 1, wherein the
hard substrate is a mirror or a transparent hard substrate.
3. An antifog-film-coated article according to claim 2, wherein the
transparent hard substrate is a glass substrate.
4. An antifog-film-coated article according to claim 1, wherein the
water-absorbing composite film is formed by applying a coating
liquid for forming the water-absorbing composite film to the hard
substrate and by subjecting the coated substrate to thermal
treatment, in which the coating liquid contains an aqueous solvent,
the polyvinyl acetal resin, and the hydrolysis product or partial
hydrolysis product of the silicon alkoxide compound.
5. An antifog-film-coated article according to claim 1, wherein the
silicon alkoxide compound is a tetraalkoxysilane.
6. An antifog-film-coated article according to claim 4, which is
formed by applying an aqueous surfactant solution to the surface of
the water-absorbing composite film formed through application of
the coating liquid to the hard substrate and subsequent thermal
treatment of the coated substrate, and by subjecting the
solution-coated film to thermal treatment.
7. An antifog-film-coated article according to claim 1, wherein the
water-absorbing composite film has a thickness of 2 to 10 .mu.m.
Description
TECHNICAL FIELD
[0001] The present invention relates to an antifog-film-coated
article. More particularly, the present invention relates to an
antifog-film-coated article including a hard substrate; in
particular, a transparent hard substrate, and a water-absorbing
composite film provided on the hard substrate, the composite film
having excellent antifog property and high pencil hardness.
BACKGROUND ART
[0002] Antifog-film-coated articles each including a hard substrate
and an antifog film provided on the substrate are used in various
applications, including antifog mirrors for bathrooms, washrooms,
etc., antifog windowpanes and antifog mirrors for automobiles,
etc., and antifog windowpanes for buildings.
[0003] Regarding an antifog single-layer film formed of a
water-absorbing polymer compound, Patent Document 1 discloses an
application-type antifog agent containing, as an active component,
only a polyvinyl acetal resin, which, when applied to an object and
then dried at ambient temperature, forms an antifog film on the
object. Patent Document 2 discloses an antifog article including an
object such as a glass, mirror, or plastic film, and an antifog
layer which is formed of a polyvinyl acetal resin having a degree
of acetalization of 2 to 40 mol % and which is provided on the
surface of the object; or an antifog article including such an
object, a water-soluble resin layer provided on the surface of the
object, and an antifog layer which is formed of a polyvinyl acetal
resin having a degree of acetalization of 2 to 40 mol % and which
is provided on the water-soluble resin layer.
[0004] However, an antifog film formed through the technique
described in Patent Document 1 or 2 exhibits, even in a dried
state, poor scratch resistance, abrasion resistance, and resistance
to wiping with a wet cloth. In addition, the antifog film exhibits
further impaired performance during moisture absorption, and may
fail to be used in, for example, such a situation that the surface
of the film is wiped routinely. These problems occur for the
following reasons.
[0005] Since the antifog film is a single-layer film formed of a
water-absorbing polymer compound, the water-absorbing polymer resin
is exposed on the surface of the film, and thus the film exhibits
good antifog property. However, the water-absorbing polymer resin
itself exhibits poor scratch resistance and abrasion resistance.
When a curing agent or the like is incorporated into the film, the
film exhibits increased strength, but poor water absorbability,
resulting in failure to exhibit sufficient antifog performance.
[0006] Meanwhile, regarding a water-absorbing composite film
containing a polyvinyl acetal resin and an inorganic component, for
example, Patent Document 3 or 4 discloses an antifog substrate
including a water-absorbing composite film containing a polyvinyl
acetal resin having a degree of acetalization of 10 mol % or less
and a hydrolysis product or partial hydrolysis product of an
alkylsilyl isocyanate, the water-absorbing composite film having
thereon a water-repellent layer or a protective film which exhibits
water permeability and has a thickness of 3 to 10 nm.
[0007] However, a water-absorbing single-layer composite film
formed through the technique described in Patent Document 3 or 4
may fail to exhibit high film hardness and abrasion resistance
while maintaining sufficient antifog property, and thus a
protective layer must be provided on the water-absorbing composite
film. When the thickness of the protective layer is increased for
improving the hardness and abrasion resistance of the entire film,
the film exhibits impaired water permeability, and thus may lose
its antifog property. Thus, the film may fail to exhibit sufficient
antifog property while maintaining high film hardness and abrasion
resistance. These problems occur for the following reasons.
[0008] When the amount of an alkylsilyl isocyanate incorporated
into the composite film is increased, since the amount of an
inorganic component (SiO.sub.2) contained in the film structure is
increased, the film exhibits improved scratch resistance and
abrasion resistance, but impaired swelling property and
flexibility; i.e., poor water absorbability. Thus, since the film
may fail to maintain sufficient antifog property, the film must
contain only a small amount of an alkylsilyl isocyanate. Therefore,
the water-absorbing single-layer composite film may fail to exhibit
sufficient film hardness. Meanwhile, when the thickness and
hardness of the protective layer are increased for improving film
hardness and abrasion resistance, the resultant film exhibits
impaired water permeability. That is, high film hardness and
abrasion resistance may fail to be imparted to the protective
layer.
PRIOR ART DOCUMENT
Patent Document
[0009] Patent Document 1: Japanese Patent Application Laid-Open
(kokai) No. H06-157794 [0010] Patent Document 2: Japanese Patent
Application Laid-Open (kokai) No. H06-158031 [0011] Patent Document
3: Japanese Patent Application Laid-Open (kokai) No. 2001-146585
[0012] Patent Document 4: Japanese Patent Application Laid-Open
(kokai) No. 2001-152137
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0013] In view of the foregoing, an object of the present invention
is to provide an antifog-film-coated article including an antifog
film having high hardness while maintaining sufficient antifog
performance, which article can be employed in various applications,
including antifog mirrors, windowpanes for automobiles, and
windowpanes for buildings.
Means for Solving the Problems
[0014] In order to achieve the aforementioned object, the present
inventors have conducted extensive studies, and as a result have
obtained the following findings.
[0015] The present inventors have found that the aforementioned
object can be achieved by forming, on a hard substrate, a
water-absorbing composite film containing, in specific proportions,
a polyvinyl acetal resin, a hydrolysis product or partial
hydrolysis product of a silicon alkoxide compound, and colloidal
silica having an average particle diameter of about 5 to about 50
nm, which is an optional component.
[0016] When SiO.sub.2 fine particles (colloidal silica) having an
average particle diameter of about 5 to about 50 nm, serving as an
inorganic component, are incorporated in addition to the hydrolysis
product or partial hydrolysis product of the silicon alkoxide, the
amount of the inorganic component contained in the composite film
can be increased while the strength and flexibility of the film
structure are maintained at certain levels. Since fine pores are
formed in the composite film through incorporation of colloidal
silica, water is readily incorporated into the film. Therefore, the
composite film exhibits improved hardness while maintaining
sufficient antifog property.
[0017] Also, the amount of the inorganic component contained in the
composite film can be increased through incorporation of colloidal
silica. Therefore, without formation of a protective layer on the
antifog film, the film exhibits sufficient antifog performance and
exhibits such a high hardness that no scratches are formed on the
film surface even under application of a load corresponding to a
pencil hardness of 4H or more.
[0018] In the case where the amount of the inorganic component is
increased with respect to the polyvinyl acetal resin, when baking
is carried out at a high temperature for a long period of time; for
example, at 120.degree. C. for 30 minutes, curing of the composite
film proceeds, and thus the film may fail to exhibit sufficient
antifog performance, although having certain levels of film
hardness and abrasion resistance. However, when the baking
temperature and time are appropriately regulated; for example,
baking is carried out at 120.degree. C. for 10 minutes, or at
60.degree. C. for 30 minutes to 60 minutes, the composite film can
be cured while the strength and flexibility of the film structure
are maintained at certain levels. In addition, the composite film
exhibits, for example, improved hardness, abrasion resistance, and
resistance to wiping with a wet cloth, while maintaining sufficient
antifog property.
[0019] Furthermore, since the amounts of colloidal silica and the
hydrolysis product or partial hydrolysis product of the silicon
alkoxide can be increased in the antifog film, the film exhibits
sufficient antifog performance and exhibits such a high hardness
that no scratches are formed on the film surface even under
application of a load corresponding to a pencil hardness of 4H or
more.
[0020] In the case of the water-absorbing composite film containing
the polyvinyl acetal resin, colloidal silica, and the hydrolysis
product or partial hydrolysis product of the silicon alkoxide,
since fogging occurs at the surface of the composite film after
absorption of a saturated amount of water in the film, when the
film is provided with such an antifog performance that it can pass
antifog testing only by virtue of its water absorbability, the
hardness and abrasion resistance of the film may fail to be
improved. However, when a surfactant is dispersed in the
water-absorbing composite film, hydrophilicity can be imparted to
the composite film, and thus a water film is formed on the surface
of the composite film after absorption of a saturated amount of
water in the composite film, resulting in no occurrence of
fogging.
[0021] Therefore, advantageously, after formation of the
water-absorbing composite film containing the polyvinyl acetal
resin, colloidal silica, and the hydrolysis product or partial
hydrolysis product of the silicon alkoxide, a surfactant is applied
to the surface of the composite film, so that the surfactant is
dispersed in the composite film, and that the composite film
exhibits both water absorbability and hydrophilicity.
[0022] When hydrophilicity is imparted to the water-absorbing
composite film, the film exhibits sufficient antifog performance
and exhibits such a high hardness that no scratches are formed on
the film surface even under application of a load corresponding to
a pencil hardness of 6H or more. Thus, advantageously, after
formation of the water-absorbing composite film containing the
polyvinyl acetal resin, colloidal silica, and the hydrolysis
product or partial hydrolysis product of the silicon alkoxide, the
composite film is subjected to surface treatment with an aqueous
solvent, for the following reasons. When the water-absorbing
composite film is subjected to the aforementioned surface treatment
after formation of the composite film, the composite film exhibits
improved water absorbability while maintaining its hardness,
abrasion resistance, and resistance to wiping with a wet cloth. In
addition, when a surfactant is dispersed in the water-absorbing
composite film, hydrophilicity can be imparted to the composite
film, and thus a water film is formed on the surface of the
composite film after absorption of a saturated amount of water in
the composite film, resulting in no occurrence of fogging.
[0023] Thus, when hydrophilicity is imparted to the water-absorbing
composite film, the composite film exhibits such a water-absorbing
performance that it can pass freeze testing, as well as such an
antifog performance that it can pass antifog testing. In addition,
when the post-baking time is appropriately regulated, the resultant
antifog film exhibits such a high hardness that no scratches are
formed on the film surface even under application of a load
corresponding to a pencil hardness of 9H or more.
[0024] The present invention has been accomplished on the basis of
these findings.
[0025] Accordingly, the present invention provides:
[0026] (1) an antifog-film-coated article comprising a hard
substrate, and a water-absorbing composite film formed on the
substrate, characterized in that the water-absorbing composite film
contains a polyvinyl acetal resin; colloidal silica in an amount of
30 to 80 parts by mass on the basis of 100 parts by mass of the
resin; and silica-equivalent particles derived from a hydrolysis
product or partial hydrolysis product of a silicon alkoxide
compound in an amount of 5 to 55 parts by mass on the basis of 100
parts by mass of the resin;
[0027] (2) an antifog-film-coated article according to (1) above,
wherein the hard substrate is a mirror or a transparent hard
substrate;
[0028] (3) an antifog-film-coated article according to (2) above,
wherein the transparent hard substrate is a glass substrate;
[0029] (4) an antifog-film-coated article according to any of (1)
to (3) above, wherein the water-absorbing composite film is formed
by applying a coating liquid for forming the water-absorbing
composite film to the hard substrate and by subjecting the coated
substrate to thermal treatment, in which the coating liquid
contains an aqueous solvent, the polyvinyl acetal resin, and the
hydrolysis product or partial hydrolysis product of the silicon
alkoxide compound;
[0030] (5) an antifog-film-coated article according to any of (1)
to (4) above, wherein the silicon alkoxide compound is a
tetraalkoxysilane;
[0031] (6) an antifog-film-coated article according to (4) or (5)
above, which is formed by applying an aqueous surfactant solution
to the surface of the water-absorbing composite film formed through
application of the coating liquid to the hard substrate and
subsequent thermal treatment of the coated substrate, and by
subjecting the solution-coated film to thermal treatment; and
[0032] (7) an antifog-film-coated article according to any of (1)
to (6) above, wherein the water-absorbing composite film has a
thickness of 2 to 10 .mu.m.
Effects of the Invention
[0033] According to the present invention, there can be provided an
antifog article including an antifog film having a water-absorbing
function, a hydrophilic function, a sufficient antifog performance,
and a high hardness (a pencil hardness of 4H or more), which
article can be employed in various applications, including mirrors,
windowpanes for automobiles, and windowpanes for buildings.
MODES FOR CARRYING OUT THE INVENTION
[0034] The antifog-film-coated article of the present invention
will next be described.
[0035] The antifog-film-coated article of the present invention
includes a hard substrate, and a water-absorbing composite film
formed on the substrate. A characteristic feature of the
antifog-film-coated article resides in that the water-absorbing
composite film contains a polyvinyl acetal resin; colloidal silica
in an amount of 30 to 80 parts by mass on the basis of 100 parts by
mass of the resin; and silica-equivalent particles derived from a
hydrolysis product or partial hydrolysis product of a silicon
alkoxide compound in an amount of 5 to 55 parts by mass on the
basis of 100 parts by mass of the resin.
[Hard Substrate]
[0036] In the antifog-film-coated article of the present invention,
the hard substrate, which serves as a base, may be any mirror or
transparent hard substrate. No particular limitation is imposed on
the transparent hard substrate, and the transparent hard substrate
employed may be selected, as appropriate, from among plastic
substrates; for example, a polycarbonate substrate and an acrylic
resin substrate such as a polymethyl methacrylate substrate, glass
substrates, etc. Of these, a glass substrate is preferably employed
for forming a water-absorbing composite film having high pencil
hardness.
(Glass Substrate)
[0037] The glass substrate employed may be, for example, plate
glass which is generally employed for automobiles, buildings,
industrial applications, etc.; i.e., float plate glass, clear glass
and any colored glass such as green glass, or bronze glass, any
functional glass, tempered glass or the like, laminated glass and
multi-layer glass or any plate glass product such as a flat glass
plate or a curved glass plate.
[0038] The thickness of the glass substrate is, for example, about
1 mm to about 12 mm. Particularly, when the antifog-film-coated
article is employed for buildings, the thickness of the glass
substrate is preferably 3 mm to 10 mm, whereas when the
antifog-film-coated article is employed for automobiles, the
thickness of the glass substrate is preferably 2 mm to 5 mm.
(Plastic Substrate)
[0039] When a plastic substrate as described above, such as a
polycarbonate substrate or an acrylic resin substrate, is employed,
the thickness of the substrate is generally about 2 to about 8 mm,
preferably 3 to 6 mm.
[0040] When such a plastic substrate is employed, the surface of
the substrate on which a water-absorbing composite film is to be
formed may optionally be subjected to a surface treatment process
such as oxidation treatment or roughening treatment, for the
purpose of improving adhesion between the plastic substrate and the
water-absorbing composite film. Examples of the oxidation treatment
include corona discharge treatment, plasma treatment, chromic acid
treatment (wet type), flame treatment, hot air treatment, and
ozone/UV ray irradiation treatment. Examples of the roughening
treatment include sand blasting and treatment with a solvent. Such
a surface treatment process is appropriately selected in
consideration of the type of the plastic substrate employed.
Generally, corona discharge treatment is preferably employed from
the viewpoints of, for example, effects and operability.
[Water-Absorbing Composite Film]
[0041] In the antifog-film-coated article of the present invention,
the water-absorbing composite film formed on the surface of the
aforementioned hard substrate contains a polyvinyl acetal resin,
colloidal silica, and a hydrolysis product or partial hydrolysis
product of a silicon alkoxide compound.
(Polyvinyl Acetal Resin)
[0042] The polyvinyl acetal resin employed in the present invention
may be produced through condensation reaction between polyvinyl
alcohol and an aldehyde; i.e., acetalization of polyvinyl alcohol.
In this case, the degree of acetalization is generally 2 to 40 mol
%, preferably 3 to 30 mol %, more preferably 5 to 20 mol %. The
degree of acetalization may be determined through, for example,
.sup.13C nuclear magnetic resonance spectroscopy.
[0043] When the degree of acetalization falls within a range of 2
to 40 mol %, the resultant water-absorbing composite film exhibits
favorable water absorbability and water resistance, and sufficient
antifog property. Acetalization of polyvinyl alcohol may be carried
out through a known technique such as the precipitation method
employing an aqueous medium in the presence of an acid catalyst, or
the dissolution method employing a solvent such as an alcohol. The
polyvinyl acetal resin may be produced, from a polyvinyl acetate
resin serving as a raw material, by carrying out saponification and
acetalization in parallel.
[0044] The polyvinyl alcohol employed generally has an average
polymerization degree of 200 to 4,500, preferably 500 to 4,500.
When the average polymerization degree is 200 or more, synthesis of
polyvinyl alcohol can be attained, whereas when the average
polymerization degree is 4,500 or less, the solution viscosity does
not become excessively high, and the resultant antifog-film-coated
article is suitable for practical applications. The higher the
average polymerization degree, the more favorable the water
resistance and water absorbability of the water-absorbing composite
film.
[0045] The polyvinyl alcohol employed generally has a
saponification degree of 75 to 99.8 mol %. When the saponification
degree is 75 mol % or more, sufficient solubility is achieved
during reaction, whereas when the saponification degree is 99.8 mol
% or less, synthesis of polyvinyl alcohol can be attained. The
lower the saponification degree, the more favorable the water
absorbability of the water-absorbing composite film.
[0046] Examples of the aldehyde which is subjected to condensation
reaction with polyvinyl alcohol include aliphatic aldehydes such as
formaldehyde, acetaldehyde, butyraldehyde, hexylcarbaldehyde,
octylcarbaldehyde, and decylcarbaldehyde; aromatic aldehydes, for
example, benzaldehyde, alkyl-substituted benzaldehydes such as
2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde,
etc., and halogen-substituted benzaldehydes such as
chlorobenzaldehyde, etc.; aromatic aldehydes having, on the
aromatic ring, a substituent such as a hydroxy group, an alkoxy
group, an amino group, or a cyano group; and aldehydes having a
condensed aromatic ring, such as naphthaldehyde and
anthraldehyde.
[0047] Particularly, an aromatic aldehyde is preferably employed,
since the resultant resin exhibits favorable water absorbability,
water resistance, and transparency. Since an aromatic aldehyde
exhibits high hydrophobicity, excellent water resistance is
achieved even in the case of low degree of acetalization, and also
a large amount of hydroxyl groups remain, resulting in excellent
water absorbability.
[0048] The amount of the polyvinyl acetal resin contained in the
water-absorbing composite film is generally about 40 to about 70
mass %, preferably 40 to 60 mass %, more preferably 40 to 50 mass
%, for improvement of film hardness, water absorbability, and
antifog property.
(Colloidal Silica)
[0049] Colloidal silica contained in the water-absorbing composite
film is formed of SiO.sub.2 fine particles having an average
particle diameter of about 5 to about 50 nm. Since the
water-absorbing composite film contains colloidal silica, the
composite film has certain levels of strength and flexibility, and
the amount of the inorganic component contained in the film can be
increased. Also, since the water-absorbing composite film contains
colloidal silica, fine pores are formed in the film, and thus water
is readily incorporated into the film. Therefore, the hardness of
the film can be improved while the antifog property thereof is
maintained at a sufficient level.
[0050] When the average particle diameter of colloidal silica is
excessively large, the haze of the resultant film may increase;
i.e., the film may become turbid, whereas when the average particle
diameter of colloidal silica is excessively small, aggregation is
likely to occur, and uniform dispersion may fail to be achieved.
Therefore, the average particle diameter of colloidal silica is
preferably 5 to 50 nm, more preferably 8 to 20 nm.
[0051] The average particle diameter of colloidal silica may be
determined through, for example, the laser diffraction light
scattering method or the Coulter counter method.
[0052] The colloidal silica content of the water-absorbing
composite film is 30 to 80 parts by mass on the basis of 100 parts
by mass of the aforementioned polyvinyl acetal resin. When the
colloidal silica content is 30 parts by mass or more, the resultant
composite film exhibits a pencil hardness of 4H or more, whereas
when the colloidal silica content is 80 parts by mass or less, the
resultant water-absorbing composite film exhibits improved
hardness, and the water absorbability and antifog performance of
the film are not impaired during the prebaking treatment described
hereinbelow.
[0053] For improvement of pencil hardness, the colloidal silica
content of the water-absorbing composite film is preferably 50 to
80 parts by mass on the basis of 100 parts by mass of the polyvinyl
acetal resin.
(Silicon Alkoxide Compound)
[0054] The water-absorbing composite film contains, as an essential
component, a hydrolysis product or partial hydrolysis product of a
silicon alkoxide compound.
[0055] The silicon alkoxide compound employed is preferably a
tetraalkoxysilane which can be readily hydrolyzed in an inorganic
acid such as hydrochloric acid, sulfuric acid, or nitric acid, or
in an organic acid such as p-toluenesulfonic acid, methanesulfonic
acid, trichloroacetic acid, or trifluoroacetic acid, to thereby
form silica. The four alkoxy groups of such a tetraalkoxysilane may
be identical to or different from one another. However, in
consideration of easy availability, a tetraalkoxysilane in which
all the four alkoxy groups are the same is generally employed. From
the viewpoint of hydrolysis, the alkoxy group is preferably a lower
alkoxy group having 1 to 4 carbon atoms.
[0056] Examples of the tetraalkoxysilane include
tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane,
tetraisopropoxysilane, tetra-n-butoxysilane, tetraisobutoxysilane,
tetra-sec-butoxysilane, and tetra-tert-butoxysilane. These
tetraalkoxysilanes may be employed singly or in combination of two
or more species.
[0057] In the present invention, the water-absorbing composite film
is required to contain silica-equivalent particles derived from the
hydrolysis product or partial hydrolysis product of the silicon
alkoxide in an amount of 5 to 55 parts by mass on the basis of 100
parts by mass of the aforementioned polyvinyl acetal resin. The
amount of silica-equivalent particles derived from the hydrolysis
product or partial hydrolysis product of the silicon alkoxide is
calculated from the amount of the silicon alkoxide employed, under
the assumption that 1 mol of SiO.sub.2 is formed from 1 mol of the
silicon alkoxide. The amount of the silica-equivalent particles
contained in the water-absorbing composite film is 5 parts by mass
or more, the water-absorbing composite film exhibits favorable
antifog performance and high pencil hardness. Meanwhile, when the
amount of the silica-equivalent particles contained in the
water-absorbing composite film is 55 parts by mass or less, silking
does not occur on the surface of the composite film; i.e., the
composite film has a smooth surface. From the aforementioned
viewpoints, the amount of the silica-equivalent particles is
preferably 20 to 55 parts by mass, more preferably 30 to 55 parts
by mass, on the basis of 100 parts by mass of the polyvinyl acetal
resin.
[0058] Next will be described a method for forming a
water-absorbing composite film on a hard substrate.
[Formation of Water-Absorbing Composite Film]
[0059] For formation of a water-absorbing composite film on the
aforementioned hard substrate, firstly, a coating liquid for
forming the water-absorbing composite film is prepared.
(Coating Liquid for Forming Water-Absorbing Composite Film)
[0060] The coating liquid for forming a water-absorbing composite
film (hereinafter may be referred to simply as "coating liquid")
may be prepared through the below-described method.
[0061] Specifically, a polyvinyl acetal resin, colloidal silica,
and a silicon alkoxide compound are added in respective specific
proportions to a solvent so that the amounts of these components
contained in the resultant water-absorbing composite film satisfy
the aforementioned requirements. Also, an appropriate amount of an
inorganic acid or an organic acid, serving as a catalyst for
hydrolysis of the silicon alkoxide compound, is added to the
resultant mixture. In addition, any additive is optionally added to
the mixture, to thereby prepare a coating liquid for forming a
composite film, the coating liquid having a solid content of about
3 to about 20 mass %.
<Solvent>
[0062] The solvent employed in the coating liquid is preferably an
aqueous solvent; i.e., a mixture of an organic solvent and
water.
[0063] The organic solvent employed may be a polar solvent having
miscibility with water, such as an alcohol solvent, a cellosolve
solvent, a ketone solvent, or an ether solvent.
[0064] Examples of the alcohol solvent include methanol, ethanol,
n-propanol, isopropanol, n-butanol, and sec-butanol. Examples of
the cellosolve solvent include methyl cellosolve, ethyl cellosolve,
butyl cellosolve, and derivatives thereof. Examples of the ketone
solvent include acetone, methyl ethyl ketone, and methyl isobutyl
ketone. Examples of the ether solvent include dioxane and
tetrahydrofuran.
[0065] These organic solvents may be employed singly or in
combination of two or more species.
[0066] The amount of water is preferably about 140 to about 720
parts by mass, more preferably 300 to 500 parts by mass, on the
basis of 100 parts by mass of the polyvinyl acetal resin.
<Hydrolysis Catalyst>
[0067] A catalyst for hydrolysis of a silicon alkoxide compound is
added to the coating liquid so that the coating liquid contains a
hydrolysis product or partial hydrolysis product of the silicon
alkoxide compound.
[0068] The hydrolysis catalyst employed is preferably an acid
catalyst; in particular, an inorganic acid such as hydrochloric
acid, nitric acid, or sulfuric acid, or an organic acid such as
trichloroacetic acid, trifluoroacetic acid, methanesulfonic acid,
or p-toluenesulfonic acid.
[0069] The amount of such an acid catalyst is preferably 0.001 to 2
mol/kg, which corresponds to the amount by mole of proton under the
assumption of complete dissociation of the acid.
[0070] The amount by mole of water employed for this hydrolysis is
preferably four times or more the entire amount by mole of the
silicon alkoxide compound.
<Optional Additive Component>
[0071] The coating liquid may optionally contain any known
additive, so long as the object of the present invention is not
impaired. Examples of such an additive include various surfactants
for improving water-absorbing performance, such as glycerin,
ethylene glycol, polyethylene glycol, etc.; a leveling agent; a UV
absorbent; a colorant; an antifoaming agent; a preservative; and
fillers such as silica, talc, clay, and alumina.
(Application of Coating Liquid)
[0072] The above-prepared coating liquid for forming a
water-absorbing composite film is preferably stirred at room
temperature for a specific period of time, to thereby hydrolyze the
silicon alkoxide compound to some extent. Thereafter, the coating
liquid is applied to the aforementioned hard substrate at room
temperature.
[0073] No particular limitation is imposed on the application
method. However, from the viewpoint of productivity, etc.,
application of the coating liquid may be appropriately carried out
through, for example, flow coating, spin coating, dip coating,
reverse coating, flexo printing, roll coating, curtain coating,
nozzle coating, spray coating, or screen printing.
[0074] Thus, the coating liquid is applied to the hard substrate.
Thereafter, drying is carried out generally at room temperature for
about 5 to about 20 minutes, and then thermal treatment (prebaking)
is carried out at a temperature of about 50 to about 130.degree. C.
for about 5 to about 60 minutes. Subsequently, the thus-prebaked
film is optionally subjected to the below-described post-treatment;
i.e., treatment with an aqueous surfactant solution.
<Treatment with Aqueous Surfactant Solution>
[0075] In this treatment with an aqueous surfactant solution, an
aqueous solution containing a surfactant in an amount of about 0.5
to about 15 mass % is applied to the surface of the above-prebaked
film, and then the solution-coated film is subjected to thermal
treatment (post-baking) at a temperature of about 50 to about
130.degree. C. for about 5 to about 60 minutes.
[0076] Through the treatment with the aqueous surfactant solution,
the surfactant can be dispersed in the water-absorbing composite
film, to thereby impart hydrophilicity to the composite film. Since
a water film is formed on the surface of the composite film after
absorption of a saturated amount of water in the composite film,
fogging does not occur.
[0077] In the present invention, optionally, the surface of the
prebaked film may be treated with an aqueous solvent; for example,
a mixture of water and an organic solvent having miscibility with
water, and then the thus-treated film may be subjected to treatment
with an aqueous surfactant solution.
[0078] The thus-formed water-absorbing composite film generally has
a thickness of about 2 to about 10 .mu.m, preferably 2 to 6
.mu.m.
[0079] The antifog film of the antifog-film-coated article of the
present invention exhibits a water-absorbing function (i.e., a
function of causing water droplets deposited on the surface of the
film to be absorbed into the film, to thereby prevent occurrence of
fogging) and a hydrophilic function (i.e., a function of forming a
water film from water droplets deposited on the surface of the
film, to thereby prevent occurrence of fogging). In the case where,
for example, the antifog-film-coated article is applied to a
windowpane of an automobile, the article exhibits antifog property
(formation of no water film on the surface of the antifog film), by
virtue of the aforementioned water-absorbing function, for about 10
seconds to about 3 minutes after the time when the temperature of
the inner surface of the windowpane becomes equal to or lower than
the dew point of an atmosphere inside the automobile. Thereafter,
the antifog-film-coated article exhibits antifog property
(formation of a water film on the surface of the antifog film), by
virtue of the aforementioned hydrophilic function.
[0080] The antifog-film-coated article of the present invention
includes a hard substrate; in particular, a transparent hard
substrate, and a water-absorbing composite film provided on the
hard substrate, the composite film having excellent antifog
property and high pencil hardness. The antifog-film-coated article
is suitable for use in various applications, including antifog
mirrors for bathrooms, washrooms, etc., antifog windowpanes and
antifog mirrors for automobiles, etc., and antifog windowpanes for
buildings.
EXAMPLES
[0081] The present invention will next be described in more detail
by way of Examples, which should not be construed as limiting the
invention thereto.
[0082] Properties of a glass substrate having a water-absorbing
composite film produced in each Example were determined through the
below-described methods.
(1) Appearance
[0083] A water-absorbing composite film was visually observed and
evaluated in terms of appearance, translucency, and cracking.
Evaluation was carried out according to the following criteria:
[0084] A: there are no problems;
[0085] B: there are no practical problems, although some
irregularities are formed on the surface of the film; and
[0086] C: there are problems.
(2) Antifog Property
[0087] Breath was applied to a glass substrate having a
water-absorbing composite film at room temperature (25.degree. C.)
for determining occurrence of fogging. The antifog property of the
substrate was evaluated according to the following criteria:
[0088] AA: no occurrence of fogging;
[0089] A: occurrence of fogging through application of a large
amount of breath;
[0090] B: occurrence of some fogging; and
[0091] C: the degree of fogging is equal to or higher than that in
the case of a common glass substrate.
(3) Pencil Hardness
[0092] According to the testing methods for paints of JIS K 5400,
the surface of a film was scratched five times with a pencil under
application of a load of 1 kg (9.8 N). The pencil hardness of the
film was determined on the basis of the hardness of a pencil which
had broken the film less than twice.
(4) Taber Abrasion Test
[0093] In the Taber abrasion test, a film was subjected to 500
cycles of abrasion under application of a load of 250 g by means of
a Taber abrasion tester ("5150 ABRASER," product of TABER
INDUSTRIES). The haze of the film was measured before and after the
test by means of "HGM-2DP" manufactured by Suga Test Instruments
Co., Ltd. When the difference between the haze of a film as
measured before the test and that of the film as measured after the
test was 4% or less, the film was regarded as passing the test.
[0094] A: Passed
[0095] C: Not passed
(5) Rubbing Test with Wet Cloth
[0096] In the rubbing test with a wet cloth--hereinafter will be
referred to as "wet cloth rubbing test" --a film was subjected to
250 cycles of rubbing under application of a load of 0.1
kg/cm.sup.2 by means of a rubbing tester ("HEIDON-18," product of
Shinto Scientific Co., Ltd.) attached with a flannel cloth
impregnated with 2 cm.sup.3 of water at 25.degree. C. Thereafter,
the surface of the film was visually observed for determining
whether or not any change occurred.
Example 1
[0097] To a glass container were added an alcohol solvent (trade
name "Solmix AP-7," product of Japan Alcohol Trading Co., Ltd;
solvent mixture of 85.5 mass % ethanol, 9.6 mass % n-propyl
alcohol, and 4.9 mass % isopropyl alcohol) in an amount of 26.25
mass %; purified water in an amount of 14.86 mass %; S-LEC KX-5
(trade name, product of Sekisui Chemical Co., Ltd., polyvinyl
acetal resin; 8 mass % (solid content)) in an amount of 43.75 mass
%; SNOWTEX OS (trade name, product of Nissan Chemical Industries,
Ltd., colloidal silica, amorphous silica solid content: 20 mass %)
in an amount of 11.65 mass %; p-toluenesulfonic acid (TsOH) in an
amount of 0.01 mass %; tetraethoxysilane (TEOS) in an amount of
3.47 mass %; and a leveling agent [trade name "KP-341," product of
Shin-Etsu Chemical Co., Ltd.] in an amount of 0.01 mass %. The
resultant mixture was stirred at room temperature (25.degree. C.)
for three hours, to thereby prepare a coating liquid for forming a
water-absorbing composite film. Table 1 shows the amounts of the
respective components contained in the coating liquid.
[0098] Subsequently, a soda lime silicate glass substrate
(thickness: 3.1 mm, size: 100.times.100 mm) was washed, and the
above-prepared coating liquid was applied to the glass substrate
through flow coating at a humidity of 30% RH and room temperature
(20.degree. C.). Thereafter, drying was carried out at room
temperature (20.degree. C.) for 10 minutes, and then thermal
treatment (prebaking) was carried out at 120.degree. C. for 10
minutes, to thereby produce a glass substrate having a
water-absorbing composite film. Hereinafter, the glass substrate
may be referred to as a "water-absorbing-composite-film-formed
glass substrate."
[0099] Table 2 shows the results of evaluation of properties of the
thus-produced water-absorbing-composite-film-formed glass
substrate.
Example 2
[0100] The procedure of Example 1 was repeated, except that the
amount of TEOS was changed to 5.65 mass %, and the amount of AP-7
was changed to 24.07 mass %, to thereby prepare a coating liquid
for forming a water-absorbing composite film. Table 1 shows the
amounts of the respective components contained in the coating
liquid.
[0101] Subsequently, a water-absorbing-composite-film-formed glass
substrate was produced in the same manner as in Example 1. Table 2
shows the results of evaluation of properties of the
water-absorbing-composite-film-formed glass substrate.
Example 3
[0102] A coating liquid for forming a water-absorbing composite
film was prepared in the same manner as in Example 2. Table 1 shows
the amounts of the respective components contained in the coating
liquid.
[0103] Subsequently, in the same manner as in Example 2, a soda
lime silicate glass substrate was washed, and the above-prepared
coating liquid was applied to the glass substrate through flow
coating at a humidity of 30% RH and room temperature (20.degree.
C.). Thereafter, drying was carried out at room temperature
(20.degree. C.) for 10 minutes, and then thermal treatment
(prebaking) was carried out at 120.degree. C. for 10 minutes.
Subsequently, a solution was prepared by diluting a surfactant
[trade name "Rapisol A-30," product of NOF Corporation, sodium
1,4-bis(2-ethylhexyl)sulfosuccinate] with water so as to attain a
surfactant concentration of 10 mass %, and the solution was applied
to the surface of the above-formed film, followed by drying at room
temperature, to thereby produce a
water-absorbing-composite-film-formed glass substrate. Table 2
shows the results of evaluation of properties of the
water-absorbing-composite-film-formed glass substrate.
Example 4
[0104] A coating liquid for forming a water-absorbing composite
film was prepared in the same manner as in Example 3. Table 1 shows
the amounts of the respective components contained in the coating
liquid.
[0105] Subsequently, in the same manner as in Example 3, a soda
lime silicate glass substrate was washed, and the above-prepared
coating liquid was applied to the glass substrate through flow
coating at a humidity of 30% RH and room temperature (20.degree.
C.). Thereafter, drying was carried out at room temperature
(20.degree. C.) for 10 minutes, and then thermal treatment
(prebaking) was carried out at 120.degree. C. for 10 minutes.
Subsequently, a solution was prepared by diluting a surfactant
[trade name "Rapisol A-30," product of NOF Corporation, sodium
1,4-bis(2-ethylhexyl)sulfosuccinate] with water so as to attain a
surfactant concentration of 10 mass %, and the solution was applied
to the surface of the above-formed film, followed by thermal
treatment (post-baking) at 120.degree. C. for 10 minutes, to
thereby produce a water-absorbing-composite-film-formed glass
substrate. Table 2 shows the results of evaluation of properties of
the water-absorbing-composite-film-formed glass substrate.
Example 5
[0106] A coating liquid for forming a water-absorbing composite
film was prepared in the same manner as in Example 4. Table 1 shows
the amounts of the respective components contained in the coating
liquid.
[0107] Subsequently, in the same manner as in Example 4, a soda
lime silicate glass substrate was washed, and the above-prepared
coating liquid was applied to the glass substrate through flow
coating at a humidity of 30% RH and room temperature (20.degree.
C.). Thereafter, drying was carried out at room temperature
(20.degree. C.) for 10 minutes, and then thermal treatment
(prebaking) was carried out at 120.degree. C. for 10 minutes.
Subsequently, a solution was prepared by diluting the
aforementioned surfactant with water so as to attain a surfactant
concentration of 10 mass %, and the solution was applied to the
surface of the above-formed film, followed by thermal treatment
(post-baking) at 120.degree. C. for 30 minutes, to thereby produce
a water-absorbing-composite-film-formed glass substrate. Table 2
shows the results of evaluation of properties of the
water-absorbing-composite-film-formed glass substrate.
Comparative Example 1
[0108] The procedure of Example 2 was repeated, except that
colloidal silica was not employed; the amount of AP-7 was changed
to 26.40 mass %; and the amount of purified water was changed to
24.18 mass %, to thereby prepare a coating liquid for forming a
water-absorbing composite film. Table 1 shows the amounts of the
respective components contained in the coating liquid.
[0109] Subsequently, a water-absorbing-composite-film-formed glass
substrate was produced in the same manner as in Example 2. Table 2
shows the results of evaluation of properties of the
water-absorbing-composite-film-formed glass substrate.
Comparative Example 2
[0110] The procedure of Example 1 was repeated, except that
colloidal silica was not employed; the amount of TEOS was changed
to 6.94 mass %; the amount of AP-7 was changed to 25.11 mass %; and
the amount of purified water was changed to 24.18 mass %, to
thereby prepare a coating liquid for forming a water-absorbing
composite film. Table 1 shows the amounts of the respective
components contained in the coating liquid.
[0111] Subsequently, a water-absorbing-composite-film-formed glass
substrate was produced in the same manner as in Example 1. Table 2
shows the results of evaluation of properties of the
water-absorbing-composite-film-formed glass substrate.
Comparative Example 3
[0112] The procedure of Example 2 was repeated, except that the
amount of SNOWTEX OS was changed to 5.00 mass %; the amount of AP-7
was changed to 25.40 mass %; and the amount of purified water was
changed to 20.18 mass %, to thereby prepare a coating liquid for
forming a water-absorbing composite film. Table 1 shows the amounts
of the respective components contained in the coating liquid.
[0113] Subsequently, a water-absorbing-composite-film-formed glass
substrate was produced in the same manner as in Example 2. Table 2
shows the results of evaluation of properties of the
water-absorbing-composite-film-formed glass substrate.
Comparative Example 4
[0114] The procedure of Example 2 was repeated, except that the
amount of SNOWTEX OS was changed to 15.00 mass %; the amount of
AP-7 was changed to 23.40 mass %; and the amount of purified water
was changed to 12.18 mass %, to thereby prepare a coating liquid
for forming a water-absorbing composite film. Table 1 shows the
amounts of the respective components contained in the coating
liquid.
[0115] Subsequently, a water-absorbing-composite-film-formed glass
substrate was produced in the same manner as in Example 2. Table 2
shows the results of evaluation of properties of the
water-absorbing-composite-film-formed glass substrate.
Comparative Example 5
[0116] The procedure of Example 2 was repeated, except that TEOS
was not added, and the amount of AP-7 was changed to 29.72 mass %,
to thereby prepare a coating liquid for forming a water-absorbing
composite film. Table 0.1 shows the amounts of the respective
components contained in the coating liquid.
[0117] Subsequently, a water-absorbing-composite-film-formed glass
substrate was produced in the same manner as in Example 2. Table 2
shows the results of evaluation of properties of the
water-absorbing-composite-film-formed glass substrate.
Comparative Example 6
[0118] Without addition of colloidal silica and an acid, KX-1
(trade name, product of Sekisui Chemical Co., Ltd., polyvinyl
acetal resin; 8 mass % (solid content)) and TEOS, serving as a
silica sol raw material for matrix formation, were diluted with a
solvent mixture of "Solmix AP-7" and purified water ("Solmix AP-7":
purified water=5:5 by mass), to thereby prepare a coating liquid
for forming a water-absorbing composite film, the coating liquid
having a ratio by mass of the polyvinyl acetal resin to silica of
99.5:0.5 and a solid content of 3 mass %. Table 1 shows the amounts
of the respective components contained in the coating liquid.
[0119] Subsequently, a water-absorbing-composite-film-formed glass
substrate was produced in the same manner as in Example 1. Table 2
shows the results of evaluation of properties of the
water-absorbing-composite-film-formed glass substrate.
Comparative Example 7
[0120] The procedure of Comparative Example 6 was repeated, except
that the ratio by mass of the polyvinyl acetal resin to silica was
changed to 95.0:5.0, to thereby prepare a coating liquid for
forming a water-absorbing composite film, and to produce a
water-absorbing-composite-film-formed glass substrate.
[0121] Table 1 shows the amounts of the respective components
contained in the coating liquid, and Table 2 shows the results of
evaluation of properties of the
water-absorbing-composite-film-formed glass substrate.
TABLE-US-00001 TABLE 1 Coating liquid for forming water-absorbing
Post-treatment composite film (mass %) Treatment with 10 Solmix
Purified S-LEC SNOWTEX Prebaking mass % aqueous Post-baking AP-7
water KX-5 OS TsOH TEOS KP-341 [120.degree. C., 10 min] surfactant
solution [120.degree. C., 10 min] Ex. 1 26.25 14.86 43.75 11.65
0.01 3.47 0.01 Done Not done Not done (3.5) (2.33) (1.00) Ex. 2
24.07 14.86 43.75 11.65 0.01 5.65 0.01 Done Not done Not done (3.5)
(2.33) (1.63) Ex. 3 24.07 14.86 43.75 11.65 0.01 5.65 0.01 Done
Done Not done (3.5) (2.33) (1.63) Ex. 4 24.07 14.86 43.75 11.65
0.01 5.65 0.01 Done Done Done (3.5) (2.33) (1.63) Ex. 5 24.07 14.86
43.75 11.65 0.01 5.65 0.01 Done Done Done (3.5) (2.33) (1.63) (30
min) Comp. Ex. 1 26.40 24.18 43.75 0.00 0.01 5.65 0.01 Done Not
done Not done (3.5) (1.63) Comp. Ex. 2 25.11 24.18 43.75 0.00 0.01
6.94 0.01 Done Not done Not done (3.5) (2.00) Comp. Ex. 3 25.40
20.18 43.75 5.00 0.01 5.65 0.01 Done Not done Not done (3.5) (1.00)
(1.63) Comp. Ex. 4 23.40 12.18 43.75 15.00 0.01 5.65 0.01 Done Not
done Not done (3.5) (3.00) (1.63) Comp. Ex. 5 29.72 14.86 43.75
11.65 0.01 0 0.01 Done Not done Not done (3.5) (2.33) Comp. Ex. 6
31.32 31.31 37.31 0.00 0.00 0.052 0.01 Done Not done Not done
(2.985) (0.015) Comp. Ex. 7 31.92 31.92 35.63 0.00 0.00 0.052 0.01
Done Not done Not done (2.850) (0.015) [Note] Each parenthesized
value of S-LEC KX-5 or SNOWTEX OS corresponds to solid content, and
each parenthesized value of TEOS corresponds to solid content as
reduced to SiO.sub.2. Solmix AP-7: alcohol solvent, product of
Japan Alcohol Trading Co., Ltd S-LEC KX-5: polyvinyl acetal resin,
product of Sekisui Chemical Co., Ltd., solid content: 8 mass %
SNOWTEX OS: colloidal silica, product of Nissan Chemical
Industries, Ltd., amorphous silica solid content: 20 mass % TsOH:
p-toluenesulfonic acid TEOS: tetraethoxysilane KP-341: leveling
agent, product of Shin-Etsu Chemical Co., Ltd Treatment with 10
mass % aqueous surfactant solution: application, to the surface of
a film, of a solution prepared by diluting a surfactant [trade name
"Rapisol A-30," product of NOF Corporation, sodium
1,4-bis(2-ethylhexyl)sulfosuccinate] with water so as to attain a
surfactant concentration of 10 mass %.
TABLE-US-00002 TABLE 2 Taber abra- Wet cloth Antifog Pencil sion
test rubbing test Appear- property hard- 250 g .times. 0.1
kg/cm.sup.2 .times. ance to breath ness 500 cycles 250 cycles Ex. 1
A A 4H A No change Ex. 2 A B 4H A No change Ex. 3 A AA 4H A No
change Ex. 4 A AA 8H A No change Ex. 5 A AA 9H A No change Comp.
Ex. 1 A AA 3H C Exfoliation Comp. Ex. 2 A A 2H C Exfoliation Comp.
Ex. 3 A A 4H C Partial exfoliation Comp. Ex. 4 A C 4H A No change
Comp. Ex. 5 A AA 3H A Exfoliation Comp. Ex. 6 A AA 3H C Exfoliation
Comp. Ex. 7 A AA 3H C Exfoliation
[0122] The data shown in Tables 1 and 2 indicate the following.
[0123] (1) The sample of Example 1 exhibited a pencil hardness of
4H while maintaining antifog performance, since the sample
contained the polyvinyl acetal resin, colloidal silica, and TEOS.
Also, the sample exhibited favorable abrasion resistance; i.e., a
change in haze through the Taber abrasion test was suppressed to 4%
or less. In addition, no change was observed in appearance after
the wet cloth rubbing test and antifog property with respect to
breath.
[0124] (2) The sample of Example 2 was produced in the same manner
as in the case of Example 1, except that the amount of TEOS added
was increased (i.e., the amount of SiO.sub.2 was increased).
Although the antifog property with respect to breath of the sample
of Example 2 was slightly lowered as compared with the case of
Example 1, the film hardness and abrasion resistance of the sample
of Example 2 were comparable to those of the sample of Example
1.
[0125] (3) In the sample of Example 3, the composition of the
coating liquid for forming a water-absorbing composite film was the
same as in the case of the sample of Example 2, but a solution
prepared by diluting a surfactant (trade name "Rapisol A-30,"
product of NOF Corporation, sodium
1,4-bis(2-ethylhexyl)sulfosuccinate) with water so as to attain a
surfactant concentration of 10 mass % was applied to the surface of
the thus-formed water-absorbing composite film. Since
hydrophilicity was imparted to the surface of the water-absorbing
composite film through absorption of the surfactant in the
composite film, a water film was formed on the surface of the
composite film after absorption of a saturated amount of water in
the composite film, and thus no fogging occurred. Also, the film
hardness and abrasion resistance of the sample of Example 3 were
comparable to those of the sample of Example 2.
[0126] (4) In the sample of Example 4, the composition of the
coating liquid for forming a water-absorbing composite film, and
the method for application of a surfactant were the same as in the
case of the sample of Example 3, but thermal drying (post-baking)
was carried out at 120.degree. C. for 10 minutes after application
of the surfactant to the surface of the composite film. Through
this post-baking, the composite film exhibited a pencil hardness as
high as 8H. Since the surfactant was dispersed in the
water-absorbing composite film, a water film was formed on the
surface of the composite film after absorption of a saturated
amount of water in the composite film, and thus no fogging
occurred. The sample of Example 4 passed the Taber abrasion test
and the wet cloth rubbing test.
[0127] (5) In the sample of Example 5, a solution prepared by
diluting a surfactant (trade name "Rapisol A-30," product of NOF
Corporation, sodium 1,4-bis(2-ethylhexyl)sulfosuccinate) with water
so as to attain a surfactant concentration of 10 mass % was applied
to the surface of the composite film, and then thermal treatment
was carried out at 120.degree. C. for 30 minutes. The composite
film exhibited a pencil hardness as high as 9H through the
30-minute post-baking even after application of the surfactant. The
sample of Example 5 passed the Taber abrasion test and the wet
cloth rubbing test.
[0128] (6) The sample of Comparative Example 1 was produced in the
same manner as in the case of Example 2, except that the amount of
TEOS added was increased. Since the sample exhibited sufficient
water absorbability, no fogging occurred through application of
breath. However, the sample exhibited very high haze after the
Taber abrasion test, and failed to attain sufficient abrasion
resistance. In addition, exfoliation of the composite film occurred
upon the wet cloth rubbing test.
[0129] (7) The sample of Comparative Example 2 was produced in the
same manner as in the case of Comparative Example 1, except that
the amount of TEOS added was increased. Since the amount of TEOS
was increased, irregularities were formed on the surface of the
composite film; i.e., so-called silking occurred, and the composite
film failed to have a smooth surface. The sample exhibited a pencil
hardness as low as 2H, and did not pass the Taber abrasion test and
the wet cloth rubbing test.
[0130] (8) The sample of Comparative Example 3 was produced in the
same manner as in the case of Example 2, except that the amount of
colloidal silica added was changed to 1 mass %. The sample of
Comparative Example 3 exhibited antifog property with respect to
breath superior to that of the sample of Example 2, and exhibited a
pencil hardness of 4H, which was equal to that of the sample of
Example 2. However, the sample of Comparative Example 3 exhibited
very high haze after the Taber abrasion test, and failed to exhibit
sufficient abrasion resistance. In addition, partial exfoliation of
the composite film occurred upon the wet cloth rubbing test.
[0131] (9) The sample of Comparative Example 4 was produced in the
same manner as in the case of Example 2, except that the amount of
colloidal silica added was changed to 3 mass %. The composite film
of the sample exhibited a pencil hardness as high as 4H, and the
sample passed the Taber abrasion test and the wet cloth rubbing
test. However, fogging occurred through application of breath, and
the degree of fogging was equal to that in the case of a common
glass substrate.
[0132] (10) The sample of Comparative Example 5 was produced in the
same manner as in the case of Example 2, except that TEOS was not
added. The sample exhibited a pencil hardness as high as about 3H,
and fogging did not occur even through application of a large
amount of breath. Also, the sample exhibited sufficient abrasion
resistance; i.e., a change in haze through the Taber abrasion test
was suppressed to 4% or less. However, exfoliation of the composite
film occurred upon the wet cloth rubbing test.
[0133] (11) The sample of Comparative Example 6 was produced from a
polyvinyl acetal resin (S-LEC KX-1, product of Sekisui Chemical
Co., Ltd.) and TEOS, serving as a silica sol raw material for
matrix formation, without addition of colloidal silica and an acid,
wherein the ratio by mass of the polyvinyl acetal resin to silica
was adjusted to 99.5:0.5, and the solid content was adjusted to 3
mass %. The sample of Comparative Example 6 exhibited very high
haze after the Taber abrasion test, and failed to attain sufficient
abrasion resistance, although fogging did not occur even through
application of a large amount of breath. In addition, exfoliation
of the composite film occurred upon the wet cloth rubbing test.
[0134] (12) The sample of Comparative Example 7 was produced in the
same manner as in the case of Comparative Example 6, except that
the ratio by mass of the polyvinyl acetal resin to silica was
adjusted to 99.0:5.0. Similar to the case of Comparative Example 6,
the sample of Comparative Example 7 exhibited very high haze after
the Taber abrasion test, and failed to attain sufficient abrasion
resistance, although exhibiting sufficient antifog performance;
i.e., fogging did not occur through application of breath. In
addition, exfoliation of the composite film occurred upon the wet
cloth rubbing test.
INDUSTRIAL APPLICABILITY
[0135] The antifog-film-coated article of the present invention
includes a hard substrate; in particular, a transparent hard
substrate, and a water-absorbing composite film provided on the
hard substrate, the composite film having excellent antifog
property and high pencil hardness. The antifog-film-coated article
is suitable for use in various applications, including antifog
mirrors for bathrooms, washrooms, etc., antifog windowpanes and
antifog mirrors for automobiles, etc., and antifog windowpanes for
buildings.
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